Gas-turbine engines offer good fuel economy and high power-to-weight ratio. They are, however, prodigious producers of nitrogen oxides, which are considered to be some of the most harmful air pollutants. Controlling nitrogen oxides emission is very difficult and very expensive. Another drawback is emission of particulate matter and unburned hydrocarbons, which is very harmful to human health. In view of the above, it is clear that it is highly desirable to have a system and a method of gas-turbine engine operation that eliminates the above disadvantages while retaining the fuel economy advantage. Such a system and a method are the subject of the present invention.